<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .father {
            width: 300px;
            height: 300px;
            background-color: pink;
        }
        .father::before {
            /* 内容 */
            /* content必须添加否则伪元素不生效 */
            content:'老鼠';
            color:green;
            width:100px;
            height: 100px;
            background-color: blue;

            /* 默认是行内元素，行高不生效 */
            display: block;
        }
        .father::after {
            /* 内容 */
            content: '大米';

        }
    </style>
</head>

<body>
    <div class="father">爱</div>
</body>
</html>